Who knew watching a kitten fall asleep could feel this good? I’m sure you can’t make it through this video without smiling.

Cats are among the heaviest sleepers in the animal kingdom. They have the physiology of a predator meaning spend a lot energy in pursuit of prey so they evolved to sleep a lot to restore their much needed energy for hunting time. While domestic cats don’t need to hunt for their dinner unlike their ancestors did, they still retained their sleeping patterns and may snooze for up to 18 hours a day – sometimes more if the cat is older. They are most active at dusk and dawn; in the wild this is when they hunt more intensely. However in a household setting, this is when they tend to scamper about, knocking things over and causing chaos.

Of all the times cats spend sleeping, they spend three quarters of it in light sleep. This level of sleep helps them to immediately react to everything around them even when they doze off. If a strange noise wakes them up, they are instantly aware and functional. You can say that they (metaphorically) “sleep with one eye open” to remain alert.

The other 25% of their sleep time is spent on deep sleep; this is when they are totally out and can even have dreams. As with humans, this type of sleep is important so they can regenerate their energy and stay healthy.